This invention relates to secretarial posture chairs, and more particularly, to a backrest height adjustment mechanism for such chairs.
A secretarial posture chair generally includes a backrest portion secured to the seat and legs of the chair by a vertically oriented upright post. The backrest portion of such chairs is dimensioned so as to support the small of the back of a person sitting in the chair. In early versions, the backrest for such chairs was fixedly secured to its upright support. In order to permit the chair to be usable by different persons, latter versions of such posture chairs included vertically adjustable backrests. An example of such an arrangement is found in U.S. Pat. No. 3,295,888 to Larry L. Poland, entitled BACKREST HEIGHT ADJUSTING APPARATUS FOR CHAIRS AND THE LIKE, issued Jan. 3, 1967. This patent discloses a backrest arrangement wherein the adjusting mechanism is wholly enclosed within the upholstered back portion of the chair. The adjusting apparatus permits the backrest to be stepwise adjusted in a vertical direction relative to the vertical support posts. However, the backrest does not pivot along its horizontal axis relative to the vertical support post. As a result, as the backrest is adjusted to fit different people using the chair, the top edge of the backrest will uncomfortably impinge on the user's back. Chairs are known employing an external, clearly visible mechanism which permits limited pivotal movement along the horizontal axis of the backrest. Such a mechanism is unsightly and does not adapt to modern furniture design. Heretofore an internal, totally enclosed, adjusting mechanism has not been available having the capability of limited, highly desirable, horizontal pivotal movement.